absorption
The process by which
substances in gaseous, liquid, or solid form dissolve or mix
with other
substances.
adsorption
The
attraction and adhesion of ions from an aqueous solution to
the surface of solids.
air
sparging
The process of injection of air below the
water table to strip volatile contaminants from the saturated
zone.
air stripping
A remediation
process for removing VOCs from groundwater by
aeration.
alluvial
Pertaining to,
or composed of, alluvium or deposited by a stream or running
water.
Alluvium
A general term for
clay, silt, sand and gravel, or similar unconsolidated
material deposited by a river as a sorted or semi-sorted
sediment in the bed of the river or on its floodplain or
delta.
analytical model
A
mathematical model that provides an exact or approximate
solution of a differential equation (and the associated
initial and boundary conditions) for subsurface water movement
or transport.
anisotropy
The
conditions under which one or more of the hydraulic properties
of an aquifer vary with direction. (See also
isotropy.)
aquiclude
A geologic
formation which may contain water (sometimes in appreciable
quantities), but is incapable of transmitting significant
quantities under ordinary field
conditions.
aquifer
A geologic
formation, group of formations or part of a formation that
contains saturated permeable material that yields sufficient,
economical quantities of groundwater.
aquifer
system
Two or more permeable units separated at
least locally by confining units that impede groundwater
movement but do not greatly affect the regional hydraulic
continuity of the system.
aquifer
test
See pumping
test.
aquifuge
An impervious
formation which neither contains nor transmits
water.
aquitard
A semi-pervious
geologic formation which can store water but transmits water
at a overflow rate compared to the
aquifer.
area of influence
Area
surrounding a pumping or recharging wen within which the water
table or potentiometric surface has been changed due to the
well's pumping or recharge. Also called zone of
influence.
artesian
aquifer
Commonly used expression, generally
synonymous with (but less favored term than)confined aquifer.
The term "artesian" takes its name from the basin of Artois in
France.
artesian well
A well
deriving its water from a confined ("artesian")
aquifer.
artificial recharge
The
process by which water can be injected or added to an aquifer.
Dug basins, wells, or the spread of water across the land
surface are all means of artificial
recharge.
attenuation
The process
of diminishing contaminant concentrations in groundwater, due
to filtration,biodegradation, dilution, sorption,
volatilization, and other processes.
backreamer
A tool attached to the end
of the drill string and pulled through the bore to enlarge the
hole and mix the cuttings with the drilling
fluid.
bailer
A device used to
withdraw a water sample from a small-diameter well or
piezometer. It is typically a piece of pipe having a check
valve in the bottom.
bail-down
test
A type of slug test performed by using a
bailer to remove a volume of water-from a small-diameter
well.
baseflow
That part of a
stream discharge not attributable to direct runoff from
precipitation or snowmelt, usually sustained by groundwater
discharging into the
stream.
bedrock
A general term for
the rock formation, usually solid, that underlies soil or
other unconsolidated
materials.
bentonite
An absorbent
aluminum silicate clay formed from volcanic ash. When
thoroughly mixed with water, bentonite breaks down into small
particles called platelets. The platelets plaster or shingle
off the wall of the hole and form a filter cake that cuts off
the flow of water into the surrounding sand or
gravel.
bioaugmentation
Similar to
bioremediation, but involving the introduction of organisms to
affect cleanup.
biodegradation
A
subset of biotransforination, it is the biologically mediated
conversion of a compound to more simple
products.
bioremediation
A cleanup
method involving the stimulation of naturally occurring
organic substances in the
soil.
bioventing
A process by which
air is injected into the subsurface to stimulate
biodegradation by microbes.
bore
1. A hole made in
the ground by drilling or pushing.
2. The act of making
a hole in the ground by drilling or
pushing.
BORE-GEL
A single-sack
boring fluid system, which consists of bentonite, polymer, and
soda ash,specially formulated by Baroid Drilling Fluids, Inc.,
for use in trenchless technology construction applications.
Processed from premium grade Wyoming sodium bentonite with an
extra high yield, enhanced to provide superior hole
stabilizing properties and cuttings support with improved
lubrication and torque
reduction.
box
The female thread
portion of a drill pipe.
bubbling
pressure
The pressure at which air enters
saturated zone (or air entry value or threshold
pressure).
build-up
The
potentiometric surface (or the water table) rise in the
vicinity of a' recharge wen. It is the vertical distance
between the initial and the new potentiometric surface (or the
water table in the case of an unconfined aquifer) at a given
point.
bulk density
The mass of a
soil per unit bulk volume of soil; the mass is measured after
all water has been extracted and the volume includes the
volume of the soil itself and the pore
volume.
cable sonde
A
probe or transmitter that operates with a wire attached to the
drill rack for locating purposes.
calibration
of models
Refinement of estimates of the input
parameters and boundary conditions of a model until model
results match the field-observed data. Also known as "history
matching."
caliche
A geological
formation often found in the Southwestern United States that
can be as hard as rock but more closely resembles very dry
layered clay which becomes sticky when
wet.
capillary form
Interfacial
forces between immiscible fluid phases, resulting in pressure
differences between the two phases.
capillary
fringe
The zone immediately above the water table
within which the water is drawn by capillary forces (fluid is
under tension). The capillary fringe is saturated, and it is
considered to be part of the unsaturated
zone.
carbonate
A sediment formed
by the organic or inorganic precipitation from aqueous
solution of carbonates of calcium, magnesium, or
iron.
carbonate rock
A rock
consisting chiefly of carbonate minerals, such as limestone
and dolomite.
Chinese Finger
A
woven wire device used to pull product back through the bore.
It is slipped over the outside diameter of the product and
attached to the drill string. The harder it is pulled, the
tighter it gets.
clastic
Pertaining
to a rock or sediment composed principally of broken fragments
that are derived from pre-existing rocks or minerals and that
have been transported some, distance from their places of
origin.
coarse
The term used to
denote sand and gravel. The use of bentonite in the drilling
fluid is recommended when boring in this type of soil
conditions.
compactor
A reamer that
enlarges the hole by compressing the soil as it is pulled
through the bore.
concentration
gradient
The change in concentration with distance
across a fluid medium.
CON-DETO
A
clear arnber liquid blend of water soluble anionic surfactant
manufactured by Baroid Drilling Fluids, Inc. It can be used in
conjunction with Quik-Gelo® to aid in reducing the tendency of
the hole-boring tools being stuck by
adhesive.
cone of depression
A
depression in the groundwater table (or potentiometric
surface) that has the shape of an inverted cone and develops
around a discharge well.
confined
aquifer
An aquifer bounded above and below by
confining layers of distinctly lower permeability than the
aquifer material and the one containing confined groundwater.
When a well is installed in a confined aquifer, the water
level in the well rises above the top of the
aquifer.
confining unit
A hydro
geologic unit of relatively low hydraulic conductivity,
bounding one or more aquifers. (See also aquitard, aquifuge,
and aquiclude.)
conservation
solute
A non-reactive constituent that does not
undergo chemical reaction during substance
migration.
contaminant
Toxic
substances found in soils and
groundwater.
contamination
The
degradation of natural water quality as a result of man's
activities. There is no implication of any specific limits,
since the degree of permissible contamination depends upon the
intended end use of the
water.
cosolvency
The interaction
of one or more organic contaminants that may cause them to
behave differently than if they were present alone in their
pure form.
cuttings
Soil particles,
also known as drilling spoils, created during the boring
process..Use of the proper drilling fluid will help to suspend
the cuttings which reduces the risk of getting stuck while
boring and backreaming.
Darcy's
law
An empirically derived equation for the flow
of fluids through porous media. It is based on the assumptions
that flow is laminar and inertia can be neglected, and states
that the specific discharge, q, is directly proportional to
the hydraulic conductivity, K, and the hydraulic gradient,
J.
darcy, unit
A unit of intrinsic
permeability, k (I darcy = 9.87 x 10-9 cm2). The relationship
between hydraulic conductivity, K, and the permeability, k, is
given as K = kpg/u where p is the fluid density, g is the
gravitational constant, and u is the dynamic
viscosity.
deflection
The amount of
flex applied to the drill stem while steering the
head.
density
The mass of a
substance per unit volume [ML-3] Units are pounds per cubic
foot (Ib/ft3),kilograms per cubic meter (kg/m3), or grams per
cubic centimeter
(g/cm3).
depth
Refers to the depth
of the drill head during a
bore.
desorption
See adsorption,
which is the reverse process.
diffusion
coefficient
See molecular
diffusion.
discharge area
An area
in which groundwater is discharged to the land surface,
surface water, or atmosphere. An area in which there are
upward components of hydraulic head in the aquifer.
Groundwater is flowing toward the surface in a discharge area
and may escape as a spring, seep, or base flow, or by
evaporation and
transpiration.
dispersion
The
spreading and mixing of chemical constituents in groundwater
caused by diffusion and mixing (due to microscopic variations
in velocities within and between
pores).
dispersion coefficient
A
measure of the spreading of a flowing substance due to the
nature of the porous medium(and specific substance or fluid
properties), with interconnected channels distributed at
random in all directions. Also the sum of the coefficients of
mechanical dispersion and molecular diffusion in porous
medium.
dispersivity
A property of
a porous medium (and the specific substance of fluid) that
determines the dispersion characteristics of the contaminant
in that medium by relating the components of pore velocity to
the dispersion coefficient.
distribution
(partitioning) coefficient
Relates the quantity of
a solute sorbed per unit weight of the solid phase and the
quantity of the solute dissolved in water per unit volume of
water.
DNAPL
Dense Non Aqueous
Phase Liquid. A liquid consisting of a solution of organic
compounds (e.g., chlorinated hydrocarbons) and which is denser
than water.
drainage basin
The land
area from which surface runoff drains into a
stream.
drawdown
A lowering of the water table of an
unconfined aquifer or the potentiometric surface of a confined
aquifer caused by pumping of groundwater from wells. The
vertical distance between the original water level and the new
water level.
dry hole
If not enough
drilling fluid is used, a dry hole occurs and the product
becomes lodged in the
ground.
duckbill
The drilling bit
that attaches to the front of the boring head. It mounts to
the head at an angle and also is bent. This angle is what
provides the steering capability while pushing the drill
pipe.
effective grain
size
The grain size corresponding to the 10% finer
by weight on the grain-size distribution
curve.
effective porosity
The
interconnected pore space through which fluids can pass,
expressed as a percent of bulk volume. Part of the total
porosity will be occupied by static fluid being held to
mineral surface by surface tension, so effective porosity will
be less than total porosity.
effluent
stream
See gaining stream.
entrance
pit
The area where the drill pipe enters the
ground after the drill machine is set up.
entry
angle
The angle at which the drill head enters the
ground or the degree that the rack is set
at.
EPA
The Environmental
Protection Agency. The federal authority responsible for
enforcing the various laws dealing with environmental
standards.
equipotential line
A
line in a two-dimensional groundwater flow field along which
the total hydraulic head(the groundwater potential) is
constant.
evapotranspiration,
actual
The evaporation that actually occurred
under given climatic and soil-moisture
conditions.
evapotranspiration,
potential
The evaporation that would occur under
given conditions if there were unlimited soil
moisture.
exit pit
The area where
the drill pipe exits the ground and the service lines are
pulled back in.
extraction well
A
discharge well used to remove groundwater or
air.
EZ-MUD®
A premium grade, high
molecular weight PUPA polymer manufactured by Baroid Company.
When this is added to bentonite in the drilling fluid, it
provides extended high viscosity and gel strength. It also
lowers the filtration rate and increases lubrication. It is an
excellent shale/clay stabilizer which minimizes
swelling.
Fick's
Law
The mass flux due to the molecular diffusion
is proportional to the concentration gradient and the
diffusion coefficient.
field
capacity
The amount of moisture remaining in the
soil after an extended period of gravity drainage without
additional supply of water at the soil
surface.
filter cake
The zone where
the bentonite platelets plaster or shingle off the wall of the
hole.
filtrate
The water portion of
the drilling fluid that seeps through the filter
cake.
fines
Term used to denote
clay and shale soils. The use of polymer is recommended in
these soil conditions to reduce swelling while at the same
time improving lubrication and torque
reduction.
flow
When the drilling
fluid moves or runs smoothly with unbroken continuity through
the entire length of the bore.
flowline or
pathline
The general path that a particle of water
follows under laminar flow conditions., Flow lines are
perpendicular to equipotential lines in an isotropic
aquifer.
flow model
A digital
computer model that calculates a hydraulic head field for the
modeling domain using numerical methods to arrive at an
approximate solution to the differential equation of
groundwater flow.
flow, steady
A
characteristic of a flow system, where the magnitude and
direction of specific discharge are constant in time at any
point. If the specific discharge has the same magnitude and
direction at any point, the flow is
uniform.
flow, unsteady
(transient)
A characteristic of a flow system
where the magnitude and/or direction of the specific discharge
changes with time.
forged upset
The
area at each end of a FIRESTICK drill stem where it tapers to
a larger diameter. This larger diameter is achieved by heating
the ends of the rod to temperatures in excess of 2000º F and
striking it with tremendous force in a die set. To achieve
this, the metal has to start out 3' longer than the desired
finished length of the drill stem.
frac
out
In certain conditions, the drilling fluid can
build tremendous pressure in the bore. If the pressure becomes
great enough, the ground will fracture to the surface. The
drilling fluid escapes the bore through this rupture, and the
pressure is relieved.
fracture
A
general term for any break in a rock, which includes cracks,
joints and faults.
fracture
trace
Visible on aerial photographs, fracture
traces are natural linear-drainage, soil-tonal, and
topographic alignments that are probably the surface
manifestation of underlying zones of
fractures.
front locate point
The
point in front of the drill head where the DIGITRAKTM locator
goes from + to -. This point is also referred to as the front
negative locate point.
gaining
stream
A stream or reach of a stream, the flow of
which is being increased by inflow of groundwater. Also known
as an effluent stream.
gel
strength
The ability of the drilling fluid to
support and suspend the cuttings. The use of bentonite in the
drilling fluid greatly increases these
characteristics.
geostatistics
A
methodology for the analysis of spatially correlated data. The
characteristic feature is in the use of variograms or related
techniques to quantify and model the spatial correlation
structure. Also includes various techniques such as kriging,
which utilize spatial correlation
models.
ghost
False signals
received by the locator.
glacial
drift
A general term for unconsolidated sediment
transported by glaciers and deposited directly on land or in
the sea.
glacial
outwash
Well-sorted sand, or sand and gravel,
deposited by the meltdown from a
glacier.
glacial till
A glacial
deposit composed of mostly unsorted sand, silt, clay, and
boulders and laid down directly by the melting
ice.
gravitational head
Component
of total hydraulic head related to the vertical position of a
given mass of water relative to an arbitrary
datum.
gravitational water
Water
that moves into, through, or out of a soil or rock mass under
the influence of gravity.
ground
stake
A long copper rod with a T handle and auger
bit that is screwed into the ground and attached to the boring
machine to provide an additional path for electricity to flow
in the event of an electrical
strike.
groundwater
The water
contained in interconnected pores below the water table in an
unconfined aquifer or in a confined
aquifer.
groundwater barrier
Rock
or artificial material with a relatively low permeability that
occurs (or is placed) below ground surface, where it impedes
the movement of groundwater and thus causes a pronounced
difference in the heads on opposite sides of the
barrier.
groundwater basin
General
term used to define a groundwater flow system that has defined
boundaries and may include more than one aquifer underlain by
permeable materials that are capable of storing or furnishing
a significant water supply. The basin includes both the
surface area and the permeable materials beneath
it.
groundwater divide
Ridge in the
water table, or potentiometric surface, from which groundwater
moves away at right angles in both directions. Line of highest
hydraulic head in the water table or potentiometric
surface.
groundwater flow
The
movement of water through openings in sediment and rock that
occurs in the zone of saturation.
groundwater
model
A simplified conceptual or mathematical
image of a groundwater system, describing the feature
essential to the purpose for which the model was developed and
including various assumptions pertinent to the system.
Mathematical groundwater models can include numerical and
analytical models.
groundwater
mound
Raised area in a water table or other
potentiometric surface, created by groundwater
recharge.
groundwater
recharge
Process of water addition to the
saturated zone, or the volume of water added by this
process.
HAZMAT
A
term used in the environmental industry to identify materials
classified as hazardous by the
EPA.
heat-treat
To treat metal by
alternate heating and cooling in order to produce desired
characteristics,such as increased hardness;
temper.
Henry's Law
The
relationship between the partial pressure of a compound and
its equilibrium concentration in a dilute aqueous solution
through a constant of proportionality known as the Henry's Law
Constant.
heterogeneity
Characteristic
of a medium in which material properties vary from point to
point.
homogeneity
Characteristic
of a medium in which material properties are identical
throughout. Though heterogeneity or nonunifonnity is the
characteristic of most aquifers, assumed homogeneity, with
some other additional assumptions, allows use of analytical
models as a valuable tool for approximate analyses of
groundwater movement.
hydra-lock
A
situation that has been known to occur while pulling product
through the bore. In this condition, the bore acts as a huge
hydraulic cylinder with the product string acting as a large
hydraulic ram. The drilling fluid stops flowing in the bore
and pressure begins to build. The pressure continues to build
to the point where the boring machine can no longer pull the
product string and you have a stuck situation. Increased
pullback pressure with decreased rotational pressure is an
indication that hydra-lock is occurring. This most often
occurs in very tight soil conditions such as dry clay and can
sometimes be cured by digging a burp hole to relieve the
pressure or by letting everything set for a period of time
while the pressure seeps past the product
string.
hydraulic
barrier
Modifications to a groundwater flow system
that restrict or impede movement of
contaminants.
hydraulic conductivity
(K)
Proportionality constant relating hydraulic
gradient to specific discharge, which, for an isotropic medium
and homogeneous fluid, equals the volume of water at the
existing kinematic viscosity that will move in unit time under
a unit hydraulic gradient through a unit area measured at
right angles to the direction flow. The rate of flow of water
in gallons per day through a cross section of one square foot
under a unit hydraulic gradient, at the prevailing temperature
(gpd/ft2). In the standard International System, the units are
m3/day/m2 or m/day. A coefficient of proportionality
describing the rate at which water can move through a
permeable medium. The density and kinematic viscosity of the
water must be considered in determining hydraulic
conductivity.
hydraulic conductivity,
effective
Rate of water flow through a porous
medium that contains more than one fluid (such as water and
air in the unsaturated zone), which should be specified in
terms of the fluid type,content and the existing
pressure.
hydraulic gradient
(J)
Slope of a water table or potentiometric
surface. More specifically, change in the hydraulic head per
unit of distance in the direction of the maximum rate of
decrease. The difference in hydraulic heads (hl-h2), divided
by the distance
(L) along the flowpath: J=
(hl-h2)/L.
hydraulic head
(h)
Height above a datum plane (such as mean sea
level) of the column of water that can be supported by the
hydraulic pressure at a given point in a groundwater system.
Equal to the distance between the water level in a well and
the datum plane.
hydrodynamic
dispersion
Spreading (at the macroscopic level) of
the solute front during transport resulting from both
mechanical dispersion and molecular diffusion. The process by
which groundwater containing a solute is diluted with
uncontaminated groundwater as it moves through an aquifer (see
dispersion
coefficient).
hydrogeologic
Those
factors that deal with subsurface waters and related geologic
aspects of surface waters.
hydrogeologic
parameters
Numerical parameters that describe the
hydro geologic characteristics of an aquifer such as porosity,
permeability, and transmissivity.
hydrogeologic
pressure
Pressure exerted by the weight of water
at any given point in a body of water at
rest.
hydrogeologic unit
Any soil
or rock unit or zone that has a distinct influence on the
storage or movement of groundwater because of its hydraulic
properties.
immiscible
The chemical property where
two or more liquids or phases do not readily dissolve in one
another, such as soil and
water.
impermeability
Characteristic
of geologic materials that limits their ability to transmit
significant quantities of water under the pressure gradients
normally found in the subsurface
environment.
impermeable layer
An
area in the subsurface that has zero air flow. Limits the
range of influence of extraction wells in SVE
systems.
infiltration
The downward
entry of water into soil or rock.
infiltration
rate
Rate at which soil or rock under specified
conditions absorbs falling rain, melting snow, or surface
water; expressed in depth of water per unit time. Also, the
maximum rate at which water can enter soil or rock under
specific conditions, including the presence of an excess of
water; expressed in units of velocity.
influent
stream
See losing
stream.
insitu
Latin term for "in
the site," used in environmental industry to describe the
treatment of contaminants without removal from their immediate
location.
intrinsic
permeability
Pertaining to the relative ease with
which a porous medium can transmit a liquid under a hydraulic
or potential gradient. It is a property of the porous medium
and is independent of the nature of the liquid or the
potential field.
isochron
A line
connecting all points having the same time of travel for
contaminant particles to move through the saturated zone and
reach a well.
isotropy
The
condition in which the properties of interest (generally
hydraulic properties of the aquifer) are the same in all
directions.
joint
Where the male and female threads
of the drill stem come together.
kinematic viscosity
The ratio of
dynamic viscosity to mass density. It is obtained by dividing
dynamic viscosity by the fluid density. Units of kinematic
viscosity are square meters per second
(M2/S).
klinkenberg effect
Gas
slippage along pore walls. Darcy's Law assumes that the
velocity of a fluid at the pore wall surface is
zero.
kriging
A
weight-moving-average interpolation method where the set of
weights assigned to samples minimizes the estimation variance,
which is computed as a function of the variogram model and
locations of the samples relative to each other, and to the
point or block being estimated.
laminar flow
Fluid flow in which the
head loss is proportional to the first power of the
velocity;synonymous with streamline flow and viscous flow.
Type of flow in which the fluid particles follow paths that
are smooth, straight, and parallel to the channel wars. In
laminar flow, the viscosity of the fluid dampens out turbulent
motion.
leaching
Removal of
materials in solution from rock, soil, or waste; dissolving
out of soluble constituents from a porous medium by
percolation of water.
leakage
Flow
of water from one hydrogeologic unit to another. This may be
natural, as through a somewhat permeable confining layer, or
anthropogenic, as through an uncased well. It may also be the
natural loss of water from artificial structures, as a result
of hydrostatic pressure.
leakage
coefficient
The rate of flow across a unit
(horizontal) area of a semi-pervious layer into (or out of) an
aquifer under one unit of head difference across this
layer.
leaky aquifer
An artesian or
water table aquifer that loses or gains water through adjacent
semipermeable confining
units.
LNAPL
Lighter-than-water non
aqueous phase liquid.
locator
The
unit which picks up the signal from the drill head where the
transmitter is housed.
losing
stream
A stream or reach of a stream that is
losing water by seepage into the ground. Also known as an
influent stream.
lubricity
Slick or
slippery as in lubricate. Polymer in the drilling fluid will
increase "lubricity" in the bore.
macropores
Relatively large pores in
porous medium that allow the enhanced movement of liquid and
gas.
make-up
The fitting together
of the pin and box sections of the drill
stem.
mats
Stainless steel wire
mesh that is part of the strike alert and grounding system.
The function of the mats is to equalize the voltage around the
machine in the event of an electrical
strike.
matrix
Solid framework of a
porous material or system.
mechanical
dispersion
Process whereby solutes are
mechanically mixed during advective transport, caused by the
velocity variations at the microscopic level; synonymous with
hydraulic dispersion. The coefficient of mechanical dispersion
is the component of mass transport flux of solutes caused by
velocity variations at the microscopic
level.
moisture content
See water
content.
molecular
diffusion
Process in which solutes are transported
at the microscopic level due to variations in the solute
concentrations within the fluid
phases.
monitoring well
A tube or
pipe, open to the atmosphere at the top and to water at the
bottom, usually along an interval of slotted screen, used for
taking groundwater
samples.
mud
Drilling
fluid.
NAPL
Non
aqueous phase liquids.
negative
locate
One of two points where a Digitrak locator
reading goes from + to -.
nonpoint
source
A source discharging pollutants into the
environment that is not a single
point.
nozzle
Located on the drill
head to spray drilling fluid into the bore.
observation well
A well drilled in a
selected location for the purpose of observing parameters such
as waterl evels and pressure changes. A non-pumping well used
to observe the elevation of the water table or the
potentiometric surface. An observation well is generally of
larger diameter than a piezometer and typically is screened or
slotted throughout the thickness of the
aquifer.
organic carbon content
The
amount of the organic carbon present in a soil. Organic
chemicals in soil adsorb to soil organic carbon and the amount
of adsorption can be related to the soil organic carbon
content.
partial
penetration
When the intake portion of the well is
less than the full thickness of the aquifer. A well
constructed in such a way that it draws water directly from a
fractional part of the total thickness of the aquifer. The
fractional part may be located at the top, the bottom, or
anywhere else in the
aquifer.
partitioning
Chemical
equilibrium condition where a chemical's concentration is
apportioned between two different phases according to the
partition coefficient, which is the ratio of a chemical's
concentration in one phase to its concentration in the other
phase.
peclet number
Relationship
between the advective and diffusive components of solute
transport;
expressed as the ratio of the product of the
average interstitial velocity and the characteristic length,
divided by the coefficient of molecular diffusion. Small
values indicate diffusion dominates; large values indicate
advection dominates.
perched
aquifer
A special case of phreatic aquifer which
occurs wherever an impervious (or semi-pervious)layer of
limited aerial extent is located between the water table of a
phreatic aquifer and the ground
surface.
perched water
Unconfined
groundwater separated from an underlying main body of
groundwater by an unsaturated
zone.
percolation
Downward movement
of water through the unsaturated zone; also defined as the
downward flow of water in saturated or nearly saturated porous
media at hydraulic gradients of 1.0 or less. The act of water
seeping or filtering through the soil without a definite
channel.
permeability
coefficient
Rate of flow of water through a unit
cross-sectional area under a unit hydraulic gradient at the
prevailing temperature (field permeability coefficient), or
adjusted to 15 degrees C.
permeability,
effective
Observed permeability of a porous medium
to one fluid phase, under conditions of physical interaction
between the phase and other fluid phases
present.
permeability,
intrinsic
Relative ease with which a porous medium
can transmit a fluid under a potential gradient,as a property
of the medium itself. Property of a medium expressing the
relative ease with which fluids can pass through
it.
phreatic aquifer
See water
table aquifer.
piezometer
A tube or
pipe, open to the atmosphere at the top and to water at the
bottom, and sealed along its length, used to measure the
hydraulic head in a geologic unit.
piezometer
surface
See potentiometric
surface.
pin
The male threads on
the drill stem.
pitch
Measurement
for the deviation from horizontal of the drill
head.
platelet
A minute, disklike
cytoplasmic body found in bentonite that plasters or shingles
off the wall of the hole to form a filter cake that cuts off
the flow of water into the surrounding sand or gravel. When
broken down to its smallest dimension, there are enough
platelets in a cubic inch of high-quality sodium bentonite to
cover 66 football fields.
point
source
Any discernible, confined, or discrete
conveyance from which pollutants are or may be discharged,
including (but not limited to) pipes, ditches, channels,
tunnels, conduits,,wells,containers, rolling stock,
concentrated animal feeding operations, or
vessels.
pollutant
Any solute or
cause of change in physical properties that renders water
unfit for a
given
use.
pollution
When the contaminant
concentration levels restrict the potential use of
groundwater.
polymer
Any of
numerous natural and synthetic compounds of usually high
molecular weight consisting of up to millions of repeated
linked units, each a relatively light and simple molecule.
Polymer, when used in conjunction with bentonite in the
drilling fluid, enhances viscosity and gel strength, lowers
filtration rate, and increases lubricity. The use of a polymer
is recommended when boring in clay or
shale.
pore space
Total space in an
aquifer medium not occupied by solid soil or rock
particles.
porosity
Ratio of the
total volume of voids to the total volume of a porous medium.
The percentage of the bulk volume of a rock or soil that is
occupied by interstices, whether isolated or connected.
Porosity may be primary, formed during deposition or
cementation of the material, or secondary formed after
deposition or cementation, such as
fractures.
positive locate
When
locating with a Digitrak&, this is the point directly
above the drill head where the locator readout changes from +
to -.
potable water
Suitable for
human consumption as drinking
water.
potentiometric surface
A
surface that represents the level to which water will rise in
wells penetrating a confined aquifer. If the head varies
significantly with depth in the aquifer, then there may be
more than one potentiometric surface. The water table is a
particular potentiometric surface for an unconfined
aquifer.
pothole
A hole dug to
expose underground utilities crossing the proposed bore
path.
pressure aquifer
Also known
as confined aquifer. (See confined
aquifer.)
pressure head
Hydrostatic
pressure expressed as the height (above a measurement point)
of a column of water that the pressure can
support.
pressure, static
Pressure
exerted by a fluid at
rest.
probe
An electronic device
that fits inside the drill head and sends out a signal used to
locate the head, read pitch and roll, and determine
depth.
PRPs
Potential responsible
parties. Waste generators who are responsible for the ultimate
fate of toxic wastes. Includes property owners, industries,
government agencies, etc. The current federal laws make the
PRPs liable in perpetuity for these
wastes.
pH
The specific gravity of
water.
public water supply
system
System for provision to the public of piped
water for human consumption. Such a system has at least 15
service connections or regularly serves at least 25
individuals daily or at least60 days out of the year. The
ten-n includes any collection, treatment, storage, and
distribution facilities under control of the operator of such
system and used primarily in connection with the system, and
any collection or pretreatment storage facilities not under
such control that are used primarily in connection with the
system.
pumping test
A test that is
conducted to determine aquifer or well characteristics. A test
made by pumping a well for a period of time and observing the
change in hydraulic head in the aquifer. A pumping test may be
used to determine the capacity of the well and the hydraulic
characteristics of the aquifer. Also called aquifer
test.
PVC
Plastic pipe that can be
used as well casing material.
quench
A step in the heat treating
process to cool hot metal which causes it to harden. The most
common quench mediums are brine, water, oil, and air. The
greatest hardness and strength for most materials are obtained
by brine or water quenching. However, this also produces the
most distortion and cracking. Oil or air quenching will
produce less distortion and cracking but also less strength
and
hardness.
QUIK-GEL®
Highest-grade
sodium bentonite manufactured by Baroid Drilling Fluids, Inc.
This drilling fluid mix develops a cost-effective low solids
slurry with high viscosity, high gel strength,and controlled
filtration rate to provide formation and hole
stabilization.
QUIK-TROL®
A white
granular pure grade polymer manufactured by Baroid Drilling
Fluids, Inc. When added to a premixed bentonite slurry, it
improves clay/shale stabilization and enhances all properties
of a bentonite slurry used in boring.
rack
The actual boring machine which
includes drive head, controls, vise,
etc.
radial flow
The flow of water
in an aquifer toward a vertical well.
radius of
influence
The radial distance from the center of a
wellbore to the point where there is no lowering of the water
table or potentiometric surface (the edge of its cone of
depression). The radial distance from an extraction well that
has adequate air flow for effective removal of contaminants
when a vacuum is applied to the extraction
well.
range of influence
The area
that can be remediated by an extraction well in an SVE
system.
Raoult's Law
A physical law
which describes the relationship between the vapor pressure of
a component over a solution, the vapor pressure of the same
component over pure liquid,and the mole fraction of the
component in the
solution.
reamer
Any of various
tools attached to the end of the drill string and pulled
through the bore to enlarge the hole and mix the cuttings with
the drilling fluid.
rear locate
point
The point behind the drill head where the
readout on a Digitrak locator switches from + to -. This is
also called the rear negative locate
point.
receiver
an electronic unit
that receives information from the transmitter. This is also
referred to as the
locator.
recharge
The addition of
water to the zone of saturation; also, the amount of water
added. Can be expressed as a rate (i.e., in/yr) or a
volume.
recharge area
An area in
which there are downward components of hydraulic head in the
aquifer. Infiltration moves downward into the deeper parts of
an aquifer in a recharge area.
recharge
basin
A basin or pit excavated to provide a means
of allowing water to soak into the ground at rates exceeding
those that would occur naturally.
recharge
boundary
An aquifer system boundary that adds
water to the aquifer. Streams and lakes are typical recharge
boundaries.
remedial
construction
T'he business of implementing the
methods for cleanup. Includes firms that specialize in
underground storage tank removal and soil vacuum
extraction.
remediation
The methods
of cleanup used for contaminated soils and
groundwaters.
remote
An auxiliary
electronic readout that displays information received from the
receiver.
residual
saturation
Saturation below which fluid drainage
will not occur.
retardation
The
movement of a solute through a geologic medium at a velocity
less than that of the flowing groundwater due to sorption or
other removal of the solute.
Reynolds
number
Dimensionless number expressing the ratio
of inertial to viscous forces acting on the fluid,Re = pVd/u.
The number can be used to determine whether the flow is
laminar or turbulent.
rockwell
The
most commonly used method for determining the hardness of a
metal.
rod
A section of drill
stem.
rod wiper
A donut-shaped
neoprene disk that fits around the drill stem to help clean it
during the pullback.
roll
The
rotational position of the drill head as it relates to a clock
face.
RPM
The speed of the drill
stem turning in the ground. It also relates to how fast the
reamer turns.
runoff
That part of
precipitation flowing to surface streams. The total amount of
water flowing in a stream. It includes overland flow, return
flow, interflow, and baseflow.
safe yield
The amount of naturally
occurring groundwater that can be withdrawn from an aquifer on
a sustained basis without impairing the native groundwater
quality or lowering water
levels.
saturation
The ratio of the
volume of a single fluid in the pores to pore volume expressed
as a percentage or a fraction.
saturated
zone
Portion of the subsurface environment in
which all voids are ideally filled with water under pressure
greater than atmospheric. The zone in which the voids in the
rock or soil are filled with water at a pressure greater than
atmospheric. The water table is the top of the saturated zone
in an unconfined aquifer.
seepage
face
Whenever a phreatic surface approaches the
downstream external boundary of a flow domain, it always
terminates on it at a point that is above the water table of
the body of open water present outside the flow domain. The
segment of the boundary above the water table and below the
phreatic surface is called the seepage
face.
semiconfined
An aquifer that
has a "leaky" confining unit and displays characteristics of
both confined and unconfined aquifers. (See leaky
aquifer.)
sewer probe
This
transmitter is designed to bore sewer pipe by allowing the
bore to be on grade. The probe works on a 0. I%
readout.
site characterization
T'he
process of determining the geology, hydrology, type of
contaminants and area of contamination. Done by engineering
and consulting firms.
skin
effect
The damage to the permeability in the
proximity of a well due to drilling
fluids.
slug test
A test for
estimating hydraulic conductivity of an aquifer in which a
rapid water-level change is produced in a piezometer or
monitoring wen, usually by introducing or withdrawing a "slug"
of water or a weight. The rise or decline in the water level
is monitored.
slurry wall
A
subsurface wall constructed by digging a trench and
backfilling it with a slurry and designed to prevent
groundwater flow.
soda ash
Sodium
carbonate in powdery white form used to increase the PH level
of hard water. This makes the mixing of bentonite and polymers
into the drill fluid much easier.
soil venting,
soil vapor extraction, soil vacuum extraction,
"SVE"
All describe the process of using extraction
wells as a means to deliver a vacuum in the subsurface,
thereby pulling toxic vapors to the surface to be treated by
an incineration,catalytic or absorptive
process.
solute transport
Net flux
of solute through a hydrogeologic unit, controlled by the flow
of subsurface -water and transport
mechanisms.
solute transport
model
Mathematical model used to predict the
movement of solutes (generally contaminants) in an aquifer
through time.
sonde
An electronic
device that fits inside the drill head and transmits a signal
used for locating purposes. Also referred to as a transmitter
or probe.
sorption
Processes that
remove solutes from the fluid phase and concentrate them on
the solid phase of a medium; used to encompass absorption and
adsorption.
sparging
A method of
forcing VOCs from the saturated zone into the vadose zone by
pushing air into the groundwater.
specific
capacity
The rate of discharge of water from the
well divided by the drawdown within the
well.
specific discharge
The volume
of water flowing through a unit cross-sectional area of an
aquifer.
specific drawdown
The
drawdown within a well divided by the discharge rate of water
from the well (inverse of specific
capacity).
specific gravity
The
ratio of a substance's density to the density of some standard
substance, usually water.
specific
retention
As water is being drained from the
interstices of soil, after drainage has stopped, the volume of
water retained in an aquifer per unit area and unit drop of
the water table.
specific
storage
The amount of water released from or taken
into storage per unit volume of a porous medium per unit
change in head.
specific
surface
The amount of surface area of a dispersed
system per gram or per unit volume of the dispersed
phase.
specific yield
The volume of
water that a saturated rock or soil win yield by gravity
(often used as a synonym for effective porosity or storage
coefficient of unconfined aquifers).
spiral
reamer
A specially designed back reamer that
resembles a huge wood screw. This long tapered spiral design
is well suited for pushing hard obstacles out of the
way.
spring
Discrete place where
groundwater flows naturally from rock or soil onto the land
surface or into a surface water
body.
stagnation point
A point in a
groundwater flow field at which the groundwater is not moving.
The magnitude of vectors of hydraulic head at the point are
equal but opposite in direction.
static water
level
The level of water in a well that is not
being affected by withdrawal of
groundwater.
stem
A section of
drill pipe.
step
potential
Describes the electrical voltage
differential between two points.
strike
alert
A warning system on all NAVIGATORs that is
set off by contact with an electrical power
source.
storage coefficient
The
amount of water released from or taken into storage per porous
medium column with a unit surface area per unit change in
head. (See also
storativity.)
storativity
A
dimensionless term representing the volume of water an aquifer
releases from or takes into storage per unit surface area of
the aquifer per unit change in head. It is equal to the
product of specific storage and aquifer thickness. In an
unconfined aquifer, the storativity is equivalent to the
specific yield.
Superfund
The
commonly used name for a federal law called "CERCLA." This act
designated a portion of funds to be put away by generators of
certain wastes for the research and implementation of
remediation
processes.
superposition
Principle
used for linear problems, such as confined groundwater flow,
that allows equation solutions to be added to form new
solutions. For example, if within a well field,pumping rates
of the pumped wells are known, the composite drawdown at a
point can be determined by summing the drawdown caused by each
individual pumped
well.
surfactant
A soap based
substance which acts as a wetting agent to reduce the tendency
of clay cutting to stick together. It also reduces the
tendency of boring tools becoming stuck by
adhesion.
swivel
Attaches between
the back reamer and the product being pulled back to keep the
product from twisting.
tempered
Metal that is reheated after
quenching for the purpose of making it more stress-free,
crack-free, distortion-free and slightly softening
it.
tensiometer
The instrument used
for measuring the capillary pressure in an unsaturated
zone.
thread compound
Used to
lubricate the thread and shoulder area of the drill joint.
Suitable thread compound should have a zinc base of 40-60% by
weight to withstand the pressures and torque that is applied
to the drill stem joints. Sometimes mistakenly referred to as
grease.
thrust
This occurs when you
push the drill stem into the ground without
rotating.
time of travel (TOT)
The
time required for a contaminant to move in the saturated zone
from a specific point to
well.
torque
The rotational force
applied to the drill stem
joints.
transmissivity
Rate at
which water of the prevailing kinematic viscosity is
transmitted through a unit width of the aquifer under a unit
hydraulic gradient. It is equal to an integration of the
hydraulic conductivities across the saturated part of the
aquifer perpendicular to the flow paths. The rate at which
water is transmitted through a unit width of an aquifer under
a unit hydraulic gradient. Transmissivity values are given in
gallons per minute through a vertical section of an aquifer
one foot wide and extending the full saturated height of an
aquifer under a hydraulic gradient of one in the English
Engineering System; in the Standard International System,
transmissivity is given in cubic meters per day through a
vertical section of an aquifer one meter wide and extending
the full saturated height of an aquifer under a hydraulic
gradient of one. It Is a function of properties of the liquid,
the porous media, and the thickness of the porous
media.
transmitter
An electronic
device that fits inside the drill head and transmits a signal
used for locating purposes. Also referred to as a sonde or
probe.
turbulent flow
Water flow in
which the flow lines are confused and heterogeneously mixed.
It is typical of flow in surface water bodies (2). That type
of flow in which the fluid particles move ' along very
irregular paths. Momentum can be exchanged between one portion
of the fluid and another. Compare with laminar
flow.
unconfined
Conditions in which the
upper surface of the zone of saturation forms a water table
under atmospheric pressure.
unconfined
aquifer
See water table
aquifer.
unconsolidated aquifer
An
aquifer made up of loose material, such as sand or gravel,
that has not undergone
lithification.
unsaturated
flow
Movement of water in porous medium in which
the pore spaces are not completely filled with
water.
unsaturated zone
The zone
between the land surface and the water table. It includes the
root zone,intermediate zone, and capillary fringe. The pore
spaces contain water, as well as air and other gases at less
than atmospheric pressure. Saturated bodies, such as perched
groundwater, may exist in the unsaturated zone, and water
pressure within these may be greater than atmospheric.
Replaces the older terms "zone of aeration" and "vadose
zone."
USTs
Underground storage
tanks used for the storage of fuels and other liquids. Most
have leaked contaminants into the ground around them. A
program to remove all old USTs is in place by the EPA and is
scheduled to be completed by 1998.
vadose zone
The area immediately
beneath the surface of the earth. Usually made up of soils,
small rocks, gravels, clays, etc. Above saturated
zone.
validation
The process of
determining the degree to which a model is an accurate
representation of the real world from the perspective of the
intended uses of the model.
velocity, average
interstitial
Average rate of groundwater flow in
interstices expressed as the product of hydraulic conductivity
and hydraulic gradient (specific discharge) divided by the
effective porosity. It is synonymous with average linear
groundwater velocity or effective
velocity.
verification
The
examination of the numerical technique in the computer code to
ascertain that it truly represents the conceptual model and
that there are no inherent problems with obtaining a
solution.
viscosity
The internal
friction within a fluid that causes it to resist
flow.
voc
Volatile organic
compounds, typically with a high vapor pressure and a tendency
to evaporate
rapidly.
volatilization
The
transfer of a chemical from liquid to the gas phase.
Solubility, molecular weight, and vapor pressure of the
liquid, and the nature of the air-liquid interface, affect the
rate of volatilization.
water
budget
An evaluation of all the sources of supply
and corresponding discharges with respect to an aquifer or
drainage basin.
water table
Upper
surface of a zone of saturation, where that surface is not
formed by a confining unit;water pressure in the porous medium
is equal to atmospheric pressure. The surface between the
vadose zone and the groundwater; that surface of a body of
unconfined groundwater at which the pressure is equal to that
of the atmosphere.
water table
aquifer
An aquifer in which the water table forms
the upper boundary.
well field
An
area containing two or more wells supplying a public water
supply system.
well, fully
penetrating
A well drilled to the bottom of an
aquifer, constructed in such a way that it withdraws water
from the entire thickness of the aquifer.
well
interference
The condition occurring when the area
of influence of a water well (the cone of depression)overlaps
that of a neighboring well or wells, as when the wells are
pumping from the same aquifer.
well
screen
A filtering device used to permit the flow
of liquid or air but prevents the passage of sediments or
backfill particles.
well yield
The
volume of water discharged from a well per unit
time.
wellhead
The physical
structure, facility, or devise at the land surface from or
through which groundwater flows or is pumped from subsurface,
water-bearing formations.
wellhead protection
area (VHPA)
The surface and subsurface area
surrounding a water well or well field, supplying a public
water system, through which contaminants are reasonably likely
to move toward and reach such water well or well
field.
wetting agent
A substance
that reduces the surface tension of a liquid, causing the
liquid to spread across or penetrate more easily the surface
of a solid. A soap-based wetting agent reduces the tendency of
clay cuttings to stick together. It also reduces the tendency
of boring tools becoming stuck due to
adhesion.
wilting point
The
soil-moisture content below which plants are unable to
withdraw soil moisture.
wing
cutter
A backreamer specially designed to cut,
mix, and change the form of the material that is being pulled
through to make it into a passable or manageable
form.
zone of
capture
Area surrounding a pumping well that
encompasses all areas of features that supply groundwater
recharge to the well.
zone of contribution
(ZOC)
The area surrounding a pumping well that
encompasses all areas or features that supply groundwater
recharge to the well.
zone of influence
(ZOI)
The area surrounding a pumping well within
which the water table or potentiometric surfaces have been
changed due to groundwater withdrawal.
zone of
transport (ZOT)
The area surrounding a pumping
well, bounded by an isochrone and/or isoconcentration contour,
through which a contaminant may travel and reach the
well.
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